The present invention relates to the strip stock metal working art and, more particularly, to apparatus and method for cutting continuous stock into predetermined severed lengths.
In the prior art, an infinite source of strip stock, such as that provided by a roll mill, is used to provide a wide variety of products. For example, the door frames of automotive vehicles are typically constructed from relatively rigid strip stock of a given cross-sectional configuration and having any one of a variety of different shapes and forms. The door frame is comprised of a plurality of individual members which are welded together at corner portions of the door frame. The complete door frame accomodates the window and regulator assembly and, of course, the relatively thin sheet metal body portion.
In these applications, the continuous strip stock is cut in a process utilizing a ram powered cutting die assembly in conjunction with a strip stock feeding system. In conventional bench presses, the ram is mounted within a generally C-shaped housing having an arm which slidably accomodates the ram and a bed portion upon which the cutting die rests. These presses contain a fly wheel contained within the housing which typically continually rotates and is provided with a single revolution clutch so that upon engagement of the fly wheel with the mechanism for reciprocating the ram, the ram is driven downwardly and upwardly through a single cycle. The feeding system is either mechanically linked to, or is synchronized in time relationship therewith, the mechanism for reciprocating the ram. The feeding system functions to advance the strip stock so that when the ram is actuated, the desired member is severed to a somewhat predetermined length when the ram engages the cutting die.
However, these techniques for cutting strip stock members labor with the disadvantages in that the time relationship between actuation of the ram and feeding of the strip stock does not consistently provide the desired predetermined length. That is, since the ram typically fails to return exactly to its top-dead-center (TDC), the ram must accordingly travel a greater or lesser distance during the subsequent cylce. Since distance, in this context, is also directly related to time, the desired synchronization between the strip stock feeding system and the ram movement cannot be attained. In this regard, it will be appreciated by those skilled in the art that even a small angular deviation from top-dead-center can result in a severed member which is substantially greater than or even less than the desired length. Accordingly, substantial material waste results which must be trimmed in an additional operation; and, in some cases the entire member must be scrapped -- i.e., if it is too short. This disadvantage is further aggravated by virtue of the high rates of production speed which are necessary to provide competitive productivity. For example, in a typical operation wherein strip stock members are cut to an average length of 30 inches, the desired production rate is typically on the order of 700 per hour.
These and other disadvantages are overcome by the present invention wherein there is provided apparatus and a method for precisely cutting continuous strip stock into predetermined lengths. Further, as will be explained more fully hereinafter, a preferred embodiment of the present invention readily accomodates continuous strip stock which is curved in one or more spacial directions.